❄️ Snow Day Probability & School Closure Prediction

Snow Day Calculator for Montreal - Will Schools Close Tomorrow?

Check your Montreal snow day probability before the school announcement. Instant school closure prediction based on snowfall, freezing rain, wind chill, and local conditions.

Montreal QC • Greater Montreal Area • Southern Quebec

🏛️ National Weather Service Data (USA)
🌍 Open-Meteo Forecast (Canada)
📍 Location-Based Prediction

Check Your Montreal Snow Day Chance

Enter your ZIP or Postal Code to check your snow day chance. Get a Snow Day Index score based on real weather data — specific to your region's closure patterns.

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Snow Day Index
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🍊 Confidence: --

Score reflects weather conditions vs your region's baseline closure threshold.
Not a statistical probability — see methodology.

Tomorrow's School Status Estimate

Based on Snow Day Index — not calibrated probability yet

Full Closure
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2-Hr Delay
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School Open
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⚠️ These splits are model estimates only. Closure vs. delay decisions depend on district policy, superintendent judgment, and conditions not fully captured by forecast data.

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Expected Snow
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Morning Feel
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Wind Speed
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Snow Timing
Why This Score

Each factor is scored independently — no double-counting

5-Day Snow Day Outlook

Index scores for the next 5 days · Accuracy decreases beyond 24hrs

Day Snow Index Signal

⚠️ Days 3–5 carry low forecast confidence. Use as early signal only — recheck daily as storm approaches.

Prediction History

How this prediction has changed as the forecast updates

Check back later — score history builds as you refresh predictions for this location.
Hourly Snowfall Forecast
Snow (in/hr)
Morning window (4–8 AM)
What If Scenarios

All scenarios calculated at once — see how each condition changes the score

↑↓ arrow keys · Enter to select · Esc to close
  • Tonight / Tomorrow
  • Day After Tomorrow
  • In 3 Days

ℹ️ Rural districts close at lower snow totals (longer bus routes). Private schools may set different thresholds. These are small adjustments — weather conditions drive the score.

Enter custom weather conditions to see how they affect the Snow Day Index score

❄️ Expected Snowfall 4 inches
🌡️ Morning Temperature (°F) 28°F
💨 Wind Speed (mph) 10 mph
🧊 Ice Accumulation 0 inches
⏰ Storm peaks during 4 AM – 8 AM window
⚠️ Blizzard / Winter Storm Warning active
🌧️ Freezing rain expected
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Adjust the sliders above

🗺️ Live Weather Maps

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How the Snow Day Index Works

The score is not a statistical probability — it's a structured index built from weather conditions compared against your region's baseline closure thresholds. Each variable measures something independent. We designed the algorithm to avoid double-counting the same conditions twice.

🌨️ Snowfall vs Regional Threshold (0–40 pts)

The biggest factor. Snowfall is scored against your region's typical closure threshold — not a flat national scale. 4 inches in Atlanta scores higher than 4 inches in Buffalo because Atlanta's threshold is lower. The region is built into this variable, not applied as a separate multiplier afterward.

⏰ Storm Timing (0–25 pts)

Measures only when the storm falls, not how much. A small storm peaking at 4 AM scores higher timing than a large storm at noon. This is completely independent from snowfall amount.

🧊 Ice / Freezing Rain (0–20 pts)

Scored separately from snowfall because ice is a different hazard. Even 0.1 inches of freezing rain is more dangerous than 6 inches of snow. This variable only activates if freezing rain is detected — it cannot overlap with V1.

🌡️ Extreme Cold / Wind Chill (0–15 pts)

Cold-day closures are a completely separate mechanism. Wind chill below -10°F can close schools with zero snow. This variable is not correlated with snowfall — it only contributes in genuinely extreme cold conditions.

⚠️ NWS Alert — Floor, Not Bonus

This is the most important design decision. NWS alerts are issued because of the same storm already measured in V1–V3. Adding alert points on top would count the same storm twice. Instead, alerts set a minimum floor — if the weather score is already higher, the alert adds nothing.

📊 Future Calibration

We collect actual school closure outcomes via the feedback button. Once we have enough data, we can compare score buckets to real closure rates — converting the index into a genuinely calibrated estimate. The methodology section will show this data publicly as we collect it.

Regional Closure Thresholds

Different regions have different infrastructure, plow capacity, and experience with snow. These thresholds are baseline estimates — not arbitrary coefficients — and will be updated as outcome feedback data accumulates.

Region Closure starts at Almost certain at
Deep South (AL, MS, GA, TX, LA)1"3"
Mid-South (NC, VA, TN, KY)2"5"
Pacific NW (WA, OR)2"5"
Mid-Atlantic (DC, MD, NJ, DE)3"7"
Mountain West (CO, UT, WY, MT)5"10"
Northeast (NY, MA, CT, PA)4"9"
Midwest (OH, IN, IL, MO)4"9"
Upper Midwest (MN, WI, MI)6"12"
Great Lakes (Buffalo, Erie, Cleveland)7"14"
🍁 CANADA
British Columbia (Vancouver)3"7"
Ontario (Toronto, Ottawa)8"16"
Quebec (Montreal, Quebec City)9"18"
Prairie Provinces (Calgary, Edmonton, Winnipeg)10"20"
Maritime Provinces (Halifax, Fredericton)10"20"

Data Sources

🇺🇸
USA

National Weather Service

The same government source superintendents reference when making closure decisions. Free, authoritative, and updated every 1–3 hours.

NWS • Official US Source
🇨🇦
Canada

Open-Meteo (ECMWF)

A free and accurate international weather service using the ECMWF global forecast model. NWS only covers the United States.

Open-Meteo • ECMWF Global Model

⚠️ The Snow Day Index is a decision-support tool, not a guarantee. School closure is a human decision made by your local district administrator. Always check your district’s official notification system for the final word. Forecast accuracy decreases significantly beyond 24 hours.

Frequently Asked Questions

How accurate is this snow day calculator?
Our predictions are based on real weather forecast data and a weighted scoring model that considers snowfall amount, timing, temperature, precipitation type, and your region's closure patterns. For USA locations, we use National Weather Service (NWS) data. For Canadian locations, we use Open-Meteo (ECMWF model). Short-term forecasts (12–24 hours) are most reliable. Predictions 48–72 hours out carry higher uncertainty and should be treated as early signals only.
Does this work for Canadian postal codes?
Yes. Enter your postal code (e.g. M5V 3A8 or M5V3A8) and the calculator will fetch weather for your area using Open-Meteo's global forecast model and apply Canada-specific regional closure thresholds. Canadian provinces have much higher snow tolerance than most US regions — Toronto and Ottawa typically close only at 8"+ accumulations, while the Prairie provinces (Calgary, Winnipeg) close even less frequently for snow alone.
Why does the same snow amount mean different things in different states?
Infrastructure and experience vary dramatically. Buffalo, NY maintains large plow fleets and handles 6 inches routinely. Atlanta, GA has a fraction of that equipment — 2 inches can shut the city down. Our regional closure thresholds account for this difference. These are baseline estimates — they will be refined over time as actual outcome data is collected through the feedback system.
Can freezing rain cause a snow day without much snow?
Yes. Even 0.1–0.25 inches of ice is more dangerous than 6 inches of ,255,0.8)">Mountain West (CO, UT, WY, MT)5"10" Northeast (NY, MA, CT, PA)4"9" Midwest (OH, IN, IL, MO)4"9" Upper Midwest (MN, WI, MI)6"12" Great Lakes (Buffalo, Erie, Cleveland)7"14" 🍁 CANADA British Columbia (Vancouver)3"7" Ontario (Toronto, Ottawa)8"16" Quebec (Montreal, Quebec City)9"18" Prairie Provinces (Calgary, Edmonton, Winnipeg)10"20" Maritime Provinces (Halifax, Fredericton)10"20"

Data Sources

USA: Weather data comes from the National Weather Service (NWS) — the same government source superintendents reference when making closure decisions. Free, authoritative, updated every 1–3 hours. Canada: Weather data is provided by Open-Meteo (ECMWF global forecast model), a free and accurate international weather service. NWS only covers the United States.

⚠️ The Snow Day Index is a decision-support tool, not a guarantee. School closure is a human decision made by your local district administrator. Always check your district's official notification system for the final word. Forecast accuracy decreases significantly beyond 24 hours.

Frequently Asked Questions

How accurate is this snow day calculator?
Our predictions are based on real weather forecast data and a weighted scoring model that considers snowfall amount, timing, temperature, precipitation type, and your region's closure patterns. For USA locations, we use National Weather Service (NWS) data. For Canadian locations, we use Open-Meteo (ECMWF model). Short-term forecasts (12–24 hours) are most reliable. Predictions 48–72 hours out carry higher uncertainty and should be treated as early signals only.
Does this work for Canadian postal codes?
Yes. Enter your postal code (e.g. M5V 3A8 or M5V3A8) and the calculator will fetch weather for your area using Open-Meteo's global forecast model and apply Canada-specific regional closure thresholds. Canadian provinces have much higher snow tolerance than most US regions — Toronto and Ottawa typically close only at 8"+ accumulations, while the Prairie provinces (Calgary, Winnipeg) close even less frequently for snow alone.
Why does the same snow amount mean different things in different states?
Infrastructure and experience vary dramatically. Buffalo, NY maintains large plow fleets and handles 6 inches routinely. Atlanta, GA has a fraction of that equipment — 2 inches can shut the city down. Our regional closure thresholds account for this difference. These are baseline estimates — they will be refined over time as actual outcome data is collected through the feedback system.
Can freezing rain cause a snow day without much snow?
Yes. Even 0.1–0.25 inches of ice is more dangerous than 6 inches of snow on roads. Ice cannot be plowed and road salt loses effectiveness below 15°F. Ice-related closures are common even with minimal snow accumulation.
When do schools usually announce closures?
Most school districts make the call between 4:30 AM and 6:00 AM on the morning of a potential closure. For large, clearly severe storms, some districts announce the evening before. Always check your district's official notification system for the final decision.
Does extreme cold alone cause school closures?
Yes. Wind chill below -15°F to -20°F is a standalone closure trigger in many northern districts. Students waiting at unsheltered bus stops face frostbite risk even with no snow at all.
What is the difference between a snow day and a 2-hour delay?
A 2-hour delay gives road crews extra time to clear routes before buses deploy. Districts choose this when conditions are expected to improve enough by mid-morning. A full closure means the district determined conditions will not be safe for the entire school day.
210cm Average Annual Snowfall
15cm+ Typical Closure Threshold
-40C Extreme Wind Chill Possible
114,000+ CSSDM Students

How Snow Day Calculator Works For Montreal

Montreal winters are defined by heavy snowfall, frequent freeze-thaw cycles, and dangerous ice storm events that can paralyze the city overnight. Situated on the island of Montreal where the St. Lawrence and Ottawa Rivers converge, the city experiences a humid continental climate with long, cold winters and an average of 210 centimetres of snow per season. Our Snow Day Calculator pulls real-time Environment Canada weather data for Montreal and the Greater Montreal Area, weighing snowfall accumulation, freezing rain, wind chill, and road safety to generate a school closure probability for your postal code.

Montreal's school system operates through French-language and English-language school service centres, each making independent closure decisions. The Centre de services scolaire de Montreal (CSSDM) and the English Montreal School Board (EMSB) serve the largest student populations and each communicate closures through their own channels.

Why Montreal Gets Heavy Winter Weather

Heavy Snowfall In Montreal

Montreal averages approximately 210 centimetres of snow per season, with individual storms regularly dropping 20-30 cm overnight. The city's position in the St. Lawrence Valley means it sits in the path of major winter storm systems tracking northeast along the Eastern Seaboard. These storms can rapidly intensify as they approach Montreal, making forecasting challenging and sometimes turning a moderate snow event into a major accumulation storm. Montreal's extensive snow removal infrastructure - one of the largest in the world - struggles to keep residential streets and school routes clear during peak storm periods.

St. Lawrence Valley Storm Track

Montreal sits at the junction of the St. Lawrence and Ottawa Rivers, directly in the path of major winter storm systems tracking northeast. Storms intensify as they move up the valley, often dropping significant snowfall on the city and surrounding communities.

Freeze-Thaw Cycles

Montreal's position in southern Quebec means temperatures frequently oscillate around the freezing point during winter. These freeze-thaw cycles produce some of the most dangerous conditions for school transportation - overnight rain that freezes by morning, creating invisible black ice across the entire road network.

Ice Storm Risk

Montreal is one of the most ice storm-prone cities in North America. The devastating 1998 Ice Storm left the city paralyzed for weeks. While such extreme events are rare, freezing rain events of several millimetres occur multiple times each winter, creating hazardous conditions for school buses and student walkers.

Wind Chill Extremes

Arctic air masses push through Montreal multiple times each winter, driving wind chills to -30C or colder. Students waiting at bus stops or walking to school face real frostbite risk during these events, and school service centres factor wind chill heavily into morning closure decisions.

Freezing Rain and Ice Storm Conditions

Freezing rain is the most feared winter weather event for Montreal school administrators. Unlike snowfall, which is manageable with plowing and sanding, freezing rain coats every surface with a layer of ice that makes roads, sidewalks, and school steps uniformly dangerous. School bus tires lose traction, students slip walking from home, and even well-maintained main roads become treacherous. As little as 2-3 mm of freezing rain accumulation can trigger widespread school bus cancellations and full school closures across the Montreal area.

Cold Temperatures and Wind Chill In Montreal

Montreal winters bring extended cold periods with average January temperatures around -10C and overnight lows frequently reaching -20C or below. When Arctic fronts arrive, wind chills can plunge to -35C or colder. Montreal school service centres monitor these conditions closely, as students waiting at outdoor bus stops face significant cold exposure risk. Cold-weather closures in Montreal often occur without major snowfall, driven purely by dangerous wind chill values.

Montreal School Service Centres and Snow Day Decisions

Montreal's school system is organized into French and English school service centres, each responsible for their own closure decisions based on local conditions and transportation safety.

Centre de services scolaire de Montreal (CSSDM)

The largest French-language school service centre in Quebec, serving over 114,000 students across Montreal island. The CSSDM makes centralized closure decisions and communicates through cssdm.ca, Radio-Canada, TVA, and automated parent notifications.

English Montreal School Board (EMSB)

The largest English-language school board on Montreal island, serving tens of thousands of students. The EMSB makes independent closure decisions and announces through emsb.qc.ca, CTV Montreal, CBC Montreal, and automated family notification systems.

Centre de services scolaire Marguerite-Bourgeoys (CSSMB)

Serving the western part of Montreal island including Lachine, LaSalle, and the West Island communities, CSSMB makes independent decisions that sometimes differ from central Montreal boards due to varying local conditions.

Laval and South Shore Boards

School service centres in Laval (north of Montreal) and the South Shore (Longueuil, Brossard) make independent decisions. Bridge and tunnel conditions between these areas and Montreal island are a key factor in their closure decisions.

Weather Factors That Affect Montreal School Closures

Weather Factor Low Impact Moderate Impact High Impact
Snow Accumulation Under 5 cm 5-15 cm 15 cm+ (closure likely)
Freezing Rain Trace amounts 2-5 mm accumulation 5 mm+ (closure likely)
Wind Chill Above -20C -20C to -30C Below -35C (closure risk)
Road Conditions Clear and treated Partially icy Black ice city-wide
Snowfall Rate Under 1 cm/hr 1-3 cm/hr Over 4 cm/hr (storm conditions)

How Montreal Schools Decide Snow Days

Montreal school service centres and boards monitor Environment Canada weather forecasts beginning the evening before a predicted storm. Directors review projected snowfall totals, freezing rain timing, overnight temperature trends, and road condition reports from transportation contractors. School bus viability is the primary concern - if bus routes through residential neighbourhoods are unsafe, closures follow. Announcements typically come between 5:30-6:30 AM through service centre websites, Radio-Canada, TVA, CTV Montreal, CBC Montreal, and automated parent notification systems.

Check Early

Run the calculator the night before a storm. Montreal school service centres typically announce closures by 6:00-6:30 AM. Check cssdm.ca and emsb.qc.ca for official announcements.

Watch Freezing Rain

Freezing rain is the top closure trigger in Montreal - even small amounts create dangerous conditions. Our calculator factors freezing rain probability heavily into the closure score alongside snowfall totals.

Use Your Postal Code

Weather conditions vary across Montreal island and the surrounding region. Enter your postal code for the most localized Environment Canada forecast and snow day prediction for your school service centre.

Montreal Areas Covered By Snow Day Calculator

Our calculator covers Montreal and the Greater Montreal Area, including:

Enter any Montreal area postal code to get a localized snow day prediction for your school service centre.

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